Preparation of sterile tubing sets



N. M. NESSET ETAL PREPARATION OF STERILE TUBING SETS Filed Aug. 20, 1941 'ffw Patented Apr. 23, 1946 PREPARATION OF STERILE TUBING SETS Naurice M. Nesset'. Glenvlew, and Edward J. Nawoj, Chicago, 111., assignors to Baxter Laboratories, Inc., Glenview, 111., a corporation of Delaware Application August 20, 1941, Serial No. 407,611

11 Claims. (01. 21--2) This invention relates to the preparation of sterile tubing sets and more particularly to sets employed in phlebotomy and dispensation of parenteral fluids.

' It is common hospital practice to give bulk parenteral. therapy by means of recipient sets consisting of necessary glass or metal parts connected by means of relatively heavy walled rubber tubing. Furthermore, it is the hospital practice to re-use these recipient sets and it is obvious that incident to this practice that the recipient sets be cleansed after or before each dispensation. This practice introduces a hazard to this therapy, principally by virtue of the fact that it is relatively "diificult to clean the rubber tubing. It is also a relatively expensive procedure to clean the rubber tubing as compared to cleaning the glass or metal parts.

An object of this application is to provide means and a method whereby the hazard and labor incident to cleaning the rubber tubing is obviated without increasing the cost. A further object is to provide a method and means whereby rubber tubing is kept in sterile condition and may be employed without further cleaning or sterilization. thus actually reducing the cost in such operations. Other specific objects and advantages will appear as the specification proceeds. j The invention may be employed in connection with a variety of apparatus. In the accompanying drawing one form of apparatus which may be employed is given by way of illustration, in which drawing- Figure 1 is a broken top plan view of tubing equipped with fittings which may be employed in connection with the invention; Fig. 2, a side view in elevation of an evacuated container in which the tubingis stored; and Fig. 3, a view of the con tainer with a portion thereof shown in section.

In the practice of our invention, we select rubber tubing having thin walls, or tubing of other suitable material, which will collapse under ordinary atmospheric pressure. By way of example, rubber tubing having a wall thickness of 'eleven-thousandths of an inch (.011") is found to be satisfactory. It is understood, however, that other dimensions of Wall thickness which has the characteristic of collapsing in the neighborhood of atmospheric pressur may be employed. The thickness will vary somewhat as to the quality and characteristics of the rubber tubing or tubing of, other suitable material employed.

, The rubber tubing may be closed at its ends byany suitable means. In practice, we prefer to jequlprthe ends of the tubing with metal or other rigid fittings attached to the open ends thereof. In view of the fact that thin-walled rubber tubing has an extremely low tensile strength, it is necessary to reinforce the open ends by means of rub-.

ber bands placed over the rubber tubing after the fittings have been put in place. It will be understood that the ends of the tubing may be modified to provide integral resilient means for engaging the fittings.

In the illustration given, I!) designates the thin walled rubber tubing. At one end the glass connecting fitting II is shown secured to the tubing [0 by a rubber band l2. The other end of the fitting II is closed by a resilient rubber cap l3.

The opposite end of the tubing I0 is secured to a hollow needle member M by means of a rubher band IS. The hollow needle extends into a glass vial l6 closed by a resilient plug [1. It will be noted that the closure I! through which the hollow needle extends maintains the needle centrally within the vial I 6.

Any suitable container may be employed. In the illustration given, a glass container [8 is shown. The container is provided at its neck with threads l9 which are engaged by the metal cap 20. A rubber disk 2| is employed to seal the top of the container and it is held rigidly in position by means of a metal disk or plate 22 thereabove. It will be understood that any suitable closure which will maintain a vacuum can be employed. Further, the container may be formed of metal or of any other suitable material.

In the operation of the process, the tubing with the fittings secured thereto but not yet closed, are thoroughly rinsed and filled with distilled water of satisfactory purity. The open end of one fitting is then closed by means of the rubber tip 13. 1 The closed end is then elevated, allowing the water to run out, thereby collapsing the tubing, It will be understood that a solution such as a physiological solution of sodium chloride or any other suitable solution may be used instead of distilled water. When all of the liquid has run out of the set, the remaining open end is closed by any suitable means. In the illustration given, the needle is closed by extending it through the rubber plug I'I into the vial.

.The collapsed, sealed set is then placed in the container I8, together with a small amount of water or solution and b the use of means well known to those skilled in the art a partial vacuum is mechanically drawn in the container. For example, a bell or jar connected to a source of vacuum may be. placed about the shoulders of the container l8 or may entirely enclose the container l8 and air thus removed from the container. In this operation, the cap 20 is only partially secured and in this loose condition, air is readily withdrawn. When, however, a sufiicient vacuum has been obtained, atmospheric pressure is restored and thus the rubber seal 2! engages the top of the container and forms therewith an air tight closure.

The vacuum is preferably drawn to a degree in which the air remaining in the tubing expands to a point in which it distends the rubber tubing. At this point, the container is closed. The degree of vacuum will vary somewhat 'in accordance with the size and capacity of the: glass parts.

The sealed container is now placed within an autoclave and sterilized by heat. The distended condition of the rubber walls serves to prevent adherence of the inner walls during the autoclave operation. In the autoclaving operation, the presence of moisture on the inside of the tubing insures adequate sterilization on the inside of the set during the heating operation. The heating is maintained at a relatively low but efiective point for a sufiicient period to bring about a complete sterilization of the tubing and set. v After the autoclaving and cooling, the set may be shipped to the point where it is to be used. It may be used in hospitals after a lapse of time or in field hospitals or operations. In the use of the device, it is necessary only to open the container, withdraw the tubing which collapses, remove the closure for the tubing set, attaching one end to a dispensing container and introducing the needle into the vein of the recipient.

It will be noted that the collapsing of the walls of the tube insures the substantial absence of air and in the flowing of liquid through the tubing, there is no danger of introducing air into the recipient,

Instead of producing a vacuum by mechanical means, it will be understood that such a vacuum may be produced by the use of heat. Heating the container causes the air to expand and the presbe a leak in either one, the tubing will collapse. Further, the vacuum prevents oxidizing of the tubing thereby insuring an indefinite shelf life. It is also assistant in preventing discoloration. The vacuum enables the use of a light weight container and closure, for unless gases are rather thoroughly removed from the inside of the container there will be abnormal expansion and increased pressure on the inside of the sealed container during the necessary period of heat sterilization. Thus if substantial quantities of gases are present in a hermetically sealed unit, the heating of the unit during sterilization causes the gases to expand and exert a high pressure on the inside of the container, Accordingly, such a unit must possess very strong Walls and a strong closure member,

Initially collapsing the tube serves to allow he'atsterilizing without rupturing the set. If the sure produced causes air to pass through the loosely fitting top. After the top is closed firmly and the container is cooled, a partial vacuum is found to be created within the container.

DiiTerentia-l pressures within the container may be created by utilizing a device known as a Bunsom valve in the set assembly. In the use of this method the container is loosely sealed .in such a manner as to permit egress of air during the heating and automatically or manually sealed during the cooling period, The valve on the set offers slight resistance to egress of gases from the set during the heating and automatically seals the set to prevent ingress of gases during cooling. Valve resistance insures difierential pressures within the set and container, thereby keeping tubing distended by virtue of the higher vacuum within the container due to free egress of gases from within the container itself. It is also to be understood that the resistance of the valve on the set may be so controlled as to prevent distention of tubing during heating. That is, if the valve has too much resistance the pressure of the gases within the container andoutside the tubing may exceed the pressure of the gases within the tubing and thus prevent distention of the tubing.

set is intact; i. e., without leaks in either the set assembly or in the container itself. Should there gases were not removed from the tubingbefore sealing where a loosely sealed container is used, they would expand during the heating sterilization, thereby rupturing the thin-walled tubing. Further, the collapsing of the tubing enables the operator to start the parenteral infusion without having to remove air from the set. It also permits drawing of external vacuum for the benefits already listed. p

Filling the tubing with water or solution to expedite collapse also insures adequate sterilization on the inside of the set due to residual moisture on the walls.

The placing of water in the container afterthe set has been introduced and prior to evacuation assists in preventing discoloration and likewise assists in the transfer of heat from the Walls of the container to the recipient set, which is an essential precaution due to the evacuated condition of the contents.

While any material may beemployed in making the container, glass is preferred in order to permit visual inspection of the contents. While we have shown one particular form of set and tubing, it will be understood that the glass and metal accessories vary greatly to suit the individual requirements or predestined use of the recipient set.

The method and means disclosed make it com nomically feasible to use a type of tubing which may be discarded after each use, thereby insuring greater safety in parenteral therapy. It reduces the cost of such therapy, by eliminating the need for expensive rubber tubing which can be reused and by eliminating many steps and hazards incident to the re-use of rubber tubing.

While in the foregoing description, we have set forth certain specific apparatus and certain specific steps as illustrative of the invention, it will be understood that such details of structure and such steps may be widel modified by those skilled in the art without departing from the invention.

We claim:

1. A method of preparing sterile tubing, comprising filling thin-walled tubing collapsible under atmospheric pressure with liquid, sealing one end, allowing the liquid to now out of the other end to collapse the tubing, closing the other'end, introducing the closed tube into a container and partially evacuating the container.

2. A method of preparing sterile tubing, com. prising filling thin-walled tubing collapsible under atmospheric pressure with sterile licluid, sealing oneend, allowing the liquid to flow out of the other end to collapse the tubing, closingth other end, introducing the closed tubing into a container, and evacuating the container to a degree suificient to cause the residual air within the tubing to distend the tubing.

3. A method of preparing sterile tubing, comprising filling tubing collapsible under atmospheric pressure with liquid, allowing the liquid to fiow out to collapse the tube, closing the ends of the tubing, introducing the tubing into a container, partially evacuating the container and sealing it, and heating the container to sterilize the contents.

4. A method of preparing sterile tubing, comprising filling tubing collapsible under atmospheric pressure with liquid, sealing one end, al lowing the liquid to flow out of the other end to collapse the tubing, closing the other end, introducing the tubing into a container, evacuating the container to a point sufficient to produce a distending of the tubing by the residual gas therein, and heating the container to sterilize the contents thereof.

5. A method of preparing sterile tubing sets, comprising filling, with liquid, tubing collapsible under atmospheric pressure and equipped at its ends with fittings, sealing the fitting at one end, allowing the liquid to fiow out of the other fitting to collapse the tubing, closing the other fitting, introducing the set into a container, partially evacuating the container, sealing the container, and heating the container to sterilize the contents.

6. A method of preparing a sterile tubing set,

, comprising filling, with liquid, tubing collapsible under atmospheric pressure, the tubing being equipped at one end with a connector fitting and at the other with a hollow needle, sealing the connector fitting, allowing the liquid to flow out of the hollow needle to collapse the tube, closing the needle by passing the same through a resilient closure-equipped vial, introducing'the set into a container, partially evacuating the container, sealing the container and heating the same to sterilize the contents.

'7. A method of preparing sterile tubing, comprising removing the air from a thin-walled tubing collapsible under atmospheric pressure to cause the tubing to collapse, sealing the ends of the tube, introducing the tubing into a container, partially evacuating the container to partially distend the tubing by means of the residual gas therein, and sealing the container and heating it to sterilize the contents.

8. A method of preparing sterile tubing, comprising removing air from thin-walled tubing collapsible under atmospheric pressure to cause the same to collapse, sealing the ends ofthe tubing, introducing the tubing into a container, introducing liquid into the container, partially evacuating the container, sealing the container and heating it to sterilize the contents.

9. A method of preparing sterile tubing, comprising filling tubing collapsible under atmospheric pressure with liquid, sealing one end, al-

lowing the liquid to flow out of the other end to collapse the tubing, closing the other end, introducing the tubing into a container, introducing a small quantity of liquid into the container, partially evacuating the container, sealing the same and heating the container to sterilize the contents.

10. In set apparatus for the purposes set forth, a container partially evacuated, a thin-walled tubing within said container and collapsible under atmospheric'pressure, means sealing the ends of said tubing, gas within said tubing tending to distend the same, and a removable closure for said container maintaining the partial vacuum therein.

11. In set apparatus for the purposes set forth,

a container partially evacuated, said container having a transparent portion through which the interior of the container is visible, a thin-walled tubing within said container and collapsible under atmospheric pressure, means sealing the ends of said tubing, gas Within said tubing tending to distend the same, Water in the container, and a closure for said container maintaining the same under partial vacuum,

NAURICE M, NESSE'I.

EDWARD J. NAWOJ. 

